The use of devices for sampling and measuring contained liquids is well recognized by those skilled in the art. Typically, such devices assist in determining the quantity, thickness, and relative location of various immiscible liquids which may be present within a storage tank, underground well, drum or similar container means. The devices are also used to obtain information relating to interior tank conditions, such as the possible presence of contaminants. Additionally, some of the devices permit samples of the stored fluid to be taken from the tank or container means for testing purposes.
The vast majority of prior art liquid sampling and measuring devices consist of a tubular casing, a valve, and an actuating mechanism which opens or closes the valve. The valve is usually located at the lowermost end of the tubular casing and controls whether or not liquid is permitted to flow into the tubular casing. For example, if the valve is in the open position, then liquid is permitted to flow into the tubular casing, and if the valve is in the closed position, then the opening is blocked and liquid is prohibited from entering or leaving the tubular casing. Essentially, the basic overall structures of the prior art devices are identical. However, the prior art devices differ from one another in the type of valve, the valve construction and the actuating mechanism utilized in their construction. For example, a number of the prior art devices consist of an actuating mechanism which functions to open or close the valve when the device is engaged with the bottom of the storage tank. See, e.g., U.S. Pat. No. 4,760,747 issued to Fackler and U.S. Pat. No. 4,346,519 issued to Milo. Additional prior art measuring devices include a sealing device which is comprised of a sealing plug, a sealing ring and a series of openings. A threaded sleeve engages the lower end of the tubular member and a sealing plate is attached within the outer or free end of the sleeve. During operation, the tubular member is rotated relative to the sleeve in order to cause the sealing member to be engaged or disengaged from the seat. See, U.S. Pat. No. 4,583,293 issued to Smith. The majority of prior art devices include valves and actuating mechanisms that are complex in design and function and incorporate multiple parts and complex mechanisms. The maintenance of those devices, such as decontamination and repair of the complex valving assemblies, is tedious, time-consuming and often difficult.
The majority of the known sampling and measuring devices is employed to obtain a liquid sample of the contents of a reservoir or underground tank and to determine if any contaminants exist. Those devices can also be employed to ascertain the thickness of immiscible fluid levels in the underground tank or container.
In addition to the sampling devices described supra, alternative devices exist in the prior art to determine the thickness of one liquid layer overlying another. Some of these employ sophisticated components such as electronic sensors to detect the interface between the two immiscible fluids and to determine the thickness of the immiscible layers. See, e.g., U.S. Pat. No. 4,184,363 issued to Vassilev et al. One drawback of the relatively sophisticated sampling devices is that they are costly. Some of the devices also can be time consuming operate. Additionally, several of such devices, including most of the electronic phase metering devices are prone to error when heavy contamination is present, and do not allow a sample of the liquid to be taken.
Accordingly, the need exists for a liquid sampling and measuring device that can provide a quick and accurate measurement of the thickness of various strata of immiscible fluids and yet is simple in design and construction and is straightforward to operate when taking samples.